Unitary hubs for domes or spheres

ABSTRACT

A unitary hub includes a central body and two or more tubular cylindrical prongs that can be used in conjunction with two or more struts to construct a dome or a sphere, such as a geodesic dome. The prongs have a first segment and a second segment that are disposed at an angle. The first segment has a first inner diameter and the second segment has a second inner diameter thereby creating a recess for the struts to be positioned easily and accurately within the prongs. The central body is formed from joining the two or more prongs disposed around an axial axis through a center of the central body. The central body has a top and bottom side with a spherically concaved section having a curvature. The struts may be tubular and cylindrical and can be inserted into the prongs or over the prongs.

COPYRIGHT

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The owner has no objection to the facsimile reproduction by anyone of the patent disclosure, as it appears in the Patent and Trademark Office files or records, but otherwise reserves all copyright rights whatsoever.

FIELD OF INVENTION

The present invention relates to a unitary hub having a central body and two or more tubular cylindrical prongs. The prongs have two segments that are tilted at an angle and may have different thicknesses. The central body is formed from joining the prongs disposed around an axial axis through a center of the central body. A plurality of the hubs and struts, which themselves may be tubular, can be assembled to construct a spherical structure, such as a geodesic dome or sphere. The struts may be tubular and cylindrical and can be inserted into the prongs or over the prongs. An underbelly of the hub includes a spherically concaved section having a curvature which may conform to the curvature of the dome.

BACKGROUND

Domes are generally referred to as spherical architectural structures. They have been used throughout history and originated in ancient cultures such as Persian, Hellenistic, Roman, and Chinese architecture. They are still being used in a number of contemporary building structures.

Geodesic domes generally refer to hemispherical thin-shell structures based on a geodesic polyhedron. The triangular elements of the dome are structurally rigid and distribute the structural stress. Geodesic domes have been used for shelter, work space, and entertainment purposes. They are generally constructed using hubs and struts. Conventional hubs include several components that have to be assembled, thus requiring assembly during construction. These conventional hubs do not provide easy coupling with the struts that are used to build the dome. Finally, conventional hubs do not have prongs which conform to the general shape of the dome. Accordingly, there is a need for a unitary hub that eliminates the need for assembly, that provides for easy coupling with their counterpart struts, that allows tilt angles between the axial axes of the struts, and whose bottom, surface conforms generally with the curvature of the dome.

SUMMARY

In one aspect, a unitary hub for a dome is disclosed wherein the hub comprises two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment, wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle, wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter, a central body formed from joining the two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body, wherein the hub comprises a top side and a bottom side, and wherein the surface of the bottom side comprises a spherically concaved section having a curvature.

Preferably, a length of the first straight segment is equal to 1.0 inches.

Preferably, the segment angle is equal to 12 degrees.

Preferably, the first inner diameter is equal to 133 inches.

Preferably, the second inner diameter is equal to 1.00 inches.

Preferably, each prong further comprises a tapered hole.

Preferably, an outer diameter of the first straight segment is equal to 1.60 inches and outer diameter of the second straight segment is equal to 1.70 inches.

Preferably, the hub comprises 3 prongs disposed at 0 degrees, 120 degrees, and 240 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.

Preferably, the hub comprises 4 prongs disposed at 0 degrees, 60 degrees. 120 degrees, and 180 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.

Preferably, the hub comprises 5 prongs disposed at 0 degrees, 72 degrees, 144 degrees, 216 degrees, and 288 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.

Preferably, the hub comprises 6 prongs disposed at 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.

Preferably, the top side comprises a circular cylindrical protrusion.

Preferably, a radius of curvature of the spherically concaved section is equal to 120 inches.

Preferably, a hub-strut assembly comprises a hub, said hub comprising two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment, wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle, wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter, a central body formed from joining the two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body, wherein the hub comprises a top side and a bottom side, and wherein the surface of the bottom side comprises a spherically concaved section having a curvature, said assembly further comprising two or more struts coupled with the two or more prongs.

Preferably, each of the two or more struts comprise a tubular circular cylindrical pipe. Preferably, at least one of the tubular circular cylindrical pipes is inserted into the first straight segment of one of the two or more prongs. Preferably, the first straight segment of at least one of the two or more prongs is inserted into one of the tubular circular cylindrical pipes.

Preferably, a dome assembly comprises a plurality of hub-strut assembly, said hub-strut assembly comprising a hub, said hub comprising two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment, wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle, wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter, a central body formed from joining the two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body, wherein the hub comprises a top side and a bottom side, and wherein the surface of the bottom side comprises a spherically concaved section having a curvature, said hub-strut assembly further comprising two or more struts coupled with the two or more prongs.

In another aspect, a method of constructing a unitary hub for a dome is disclosed wherein the method comprises providing two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment, wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle, wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter, and joining the two or more tubular circular cylindrical prongs to form a central body, said two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body, wherein the hub comprises a top side and a bottom side, and wherein the surface of the bottom side comprises a spherically concaved section having a curvature.

In another aspect, a method of assembling a dome is disclosed wherein the method comprises providing a plurality of unitary hubs, each unitary hub comprising two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment, wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle, wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter, and a central body formed from joining the two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body, wherein the hub comprises a top side and a bottom side, and wherein the surface of the bottom side comprises a spherically concaved section having a curvature, providing a plurality of struts coupled with the two or more prongs of each of the unitary hubs.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view of a preferred embodiment of a dome assembly comprising a plurality of hub-strut assemblies including a 6-prong, a 5-prong, and a 4-prong, unitary hubs according to the present invention.

FIG. 2 shows a top view of a preferred embodiment of a 6-prong unitary hub according to the present invention,

FIG. 3 shows a cross sectional view of the 6-prong unitary hub as shown in FIG. 2.

FIG. 4 shows an exploded view of a preferred embodiment of a 5-prong unitary hub and cutaway sections of 5 struts, wherein the first straight segments of the prongs are inserted into the struts.

FIG. 5 shows an exploded view of a preferred embodiment of a 5-prong unitary hub and cutaway sections of 5 struts, wherein the struts are inserted into the first straight segments of the prongs.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

FIG. 1 depicts a side view of a preferred embodiment of a dome assembly 100 according to the present invention. The dome assembly 100, for instance a geodesic dome assembly, comprises a plurality of hub-strut assemblies including a 6-prong hub at 104, a 5-prong hub at 102, and a 4-prong hub at 106. The 6-prong hub is coupled with 6 struts, for instance 6 tubular circular cylindrical pipes at 108, 110, 112, 114, 116, and 118. According to a preferred embodiment, the hubs are made of acrylonitrile butadiene styrene, such as the one used in the ABS piping system, and the struts are made of polyvinyl chloride, such as the one used in the PVC piping system, known to artisans of ordinary skill.

Hubs, such as the 6-prong huh 104 can be manufactured using injection molding process. Injection molding is a manufacturing process for producing parts by injecting material into a mold. A variety of materials can be used to make injection molded parts. These materials include metals (die-casting process), glasses, elastomers, confections, and most commonly thermoplastics and thermosetting polymers. According to a preferred embodiment, the material used to make the 6-prong hub 104 is the one used in the ABS piping system.

The 6-prong hub 104 can be designed using ID solid modeling such as the PTC Creo, formerly known as Pro/ENGINEER, available to purchase from the PTC corporation in Newport Beach, Calif., The 3D solid modeling is used to create the final design of the hub 104, for instance, by designing a single prong and generating 5 other prongs of the same dimensions each disposed at 60 degrees apart.

The prong has a first straight segment and a second straight segment, wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle. Two cylindrical holes of different diameters are introduced in the prong, such that the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter. A central body of the hub 104 is thus formed from joining the 6 prongs which are disposed around an axial axis through a center of the central body. As such, the central body of the hub 104 will accordingly have a circular cylindrical shape with a top side and a bottom side, and a surface of the bottom side is given a spherically concaved section having a curvature. Other manners of generating the hub 104 utilizing 3D solid modeling is contemplated and within the scope of the present invention.

FIG. 2 depicts a top view of a preferred embodiment of a 6-prong unitary hub 200, such as the hub 104 shown in FIG. 1, according to the present invention. The hub 200 comprises 6 prongs at 202, 204, 206, 208, 210, and 212. According to this configuration, each prong has a first straight segment and a second straight segment. For instance, the prong 202 has a first straight segment 214 and a second straight segment 216. The first straight segment 214 has a first length and the second straight segment has a second length and there is a segment angle θ_(S) between the two segments, as discussed in more detail below in connection with FIG. 3.

The hub 200 further includes a central body 218 which is formed from joining the prongs 202, 204, 206, 208, 210, and 212 which are disposed around an axial axis A_(H) (see FIG. 3) through a center of the central body 218. The prongs 202, 204, 206, 208, 210, and 212 are disposed around this axis at the same angle θ_(P) at 220, hence, at angles equal to 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees, measured from a transverse axis A_(T) at 224 perpendicular to the axial axis A_(H) and passing through the center of the central body 218. According to this preferred embodiment, the central body 218 is a circular disc and includes a top side having a circular cylindrical protrusion at 222.

FIG. 3 depicts a cross sectional view 300 of the 6-prong unitary hub 200 as shown in FIG. 2. This cross sectional view shows the detailed geometry of the hub 200, specifically, the two prongs 202 and 208 and the central body 218. According, to this preferred embodiment, the prong 202 comprises a first straight segment 214 and a second straight segment 216.

The first straight segment 214 has a first length L₁ at 302 and the second straight segment 216 has a second length L2 at 304. The first straight segment 214 is tilted with respect to the second straight segment 216 thereby making an angle θ_(S) at 306. A first hole 330 is cast in the first straight segment 214 and a second hole 332 is cast in the second straight segment 216. This provides for the first straight segment 214 to have a first inner diameter D_(1I) at 312 and a first outer diameter D_(1O) at 310, and for the second straight segment 216 to have a second inner diameter D_(2I) at 314 and a second outer diameter D_(2O) at 316.

The difference between the D_(1O) and D_(2O) provides for an annular recess 326 where a strut (See FIG. 4) may be butted up against said recess 326 to precisely locate the strut into which the first straight segment 214 of the prong 202 is inserted. The difference between the D_(1I) and D_(2I) provides for an annular recess 328 where a strut (See FIG. 5) may be butted up against said recess 328 to precisely locate the strut that is inserted into the first straight segment 214 of the prong 202 (See FIG. 5). In both configurations, the strut may be coupled with the prong 202 by interference fit or press-fit, known to artisans of ordinary skill.

The central body 218 is formed from joining the prongs 202, 204, 206, 208, 210, and 212 which are disposed around an axial axis A_(H) at 308 as described above in connection with FIG. 2. The central body 218 has a top side and bottom side, and the bottom side includes a spherically concaved section 324 having a curvature R at 322. In a preferred embodiment, the concaved section 324 matches the convex surface of the dome assembly 100. The top side includes a circular protrusion at 222 having a diameter P_(D) at 318 and a thickness t₁ at 320. The protrusion 222 together with the central body 218 can be used to anchor other components using bolts or screws to the dome assembly 100.

According to a preferred embodiment, the length L₁ at 302 is equal to 1.00 inches, the segment angle θS at 306 is equal to 12 degrees, the first inner diameter D_(1I) at 312 is equal to 133 inches, the first outer diameter D_(1O) at 310 is equal to 1.60 inches, the second inner diameter D_(2I) at 314 is equal to 1.00 inches, the second outer diameter D_(2O) at 316 is equal to 1.70 inches, a length L_(T) at 334 is equal to 5.67 inches, and the radius of curvature R at 322 is equal to 120 inches.

As discussed above in connection with FIG. 1, hubs having different number of prongs are contemplated. Specifically, with reference to the transverse axis A_(T) at 224 (see FIG. 2) which is perpendicular to the axial axis A_(H) at 308 passing through the center of the central body 218, a 3-prong hub has its prongs disposed at 0 degrees, 120 degrees, and 240 degrees, a 4-prong hub has its prongs disposed at 0 degrees, 60 degrees, 120 degrees, and 180 degrees, a 5-prong hub has its prongs disposed at 0 degrees, 72 degrees, 144 degrees, 216 degrees, and 288 degrees, and a 6-prong hub has its prongs disposed at 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees.

FIG. 4 depicts an exploded view 400 of a preferred embodiment of a 5-prong unitary hub and cutaway sections of 5 struts. The hub has a central body 408 and 5 prongs, one of which at 402 is shown to have a first straight segment 404 and a second straight segment 406. The first straight segment 404 includes a tapered hole 410. A strut 416 (shown as a cutaway section) may be a tubular circular cylindrical pipe. It also has a through hole 418 which becomes aligned with the tapered hole 410 after the first straight segment 404 of the prong 402 is inserted into the strut 416. A bolt 412 and a nut 414 may be used to couple the struct 416 with the prong 402.

FIG. 5 depicts an exploded view 500 of a preferred embodiment of a 5-prong unitary hub and cutaway sections of 5 struts. The hub has a central body 508 and 5 prongs, one of which at 502 is shown to have a first straight segment 504 and a second straight segment 506. The first straight segment 504 includes a tapered hole 510. A strut 516 (shown as a cutaway section) may be a tubular circular cylindrical pipe. It also has a through hole 518 which becomes aligned with the tapered hole 510 after the strut 516 is inserted into the first straight segment 504 of the prong 502. A bolt 512 and a nut 514 may be used to couple the struct 516 with the prong 502.

The foregoing explanations, descriptions, illustrations, examples, and discussions have been set forth to assist the reader with understanding this invention and further to demonstrate the utility and novelty of it and are by no means restrictive of the scope of the invention. It is the following claims, including all equivalents, which are intended to define the scope of this invention. 

What is claimed is:
 1. A unitary hub for a dome, comprising: (a) two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment; wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle; wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter; (b) a central body formed from joining the two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body; wherein the hub comprises a top side and a bottom side; and wherein the surface of the bottom side comprises a spherically concaved section having a curvature.
 2. The hub of claim 1, wherein a length of the first straight segment is equal to 1.0 inches.
 3. The hub of claim 1, wherein the segment angle is equal to 12 degrees.
 4. The hub of claim 1, wherein the first inner diameter is equal to 1.33 inches.
 5. The hub of claim 1, wherein the second inner diameter is equal to 1.00 inches.
 6. The hub of claim 1, wherein each prong further comprises a tapered hole.
 7. The hub of claim 1, wherein an outer diameter of the first straight segment is equal to 1.60 inches and outer diameter of the second straight segment is equal to 1.70 inches.
 8. The hub of claim 1, wherein the hub comprises 3 prongs disposed at 0 degrees, 120 degrees, and 240 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.
 9. The hub of claim 1, wherein the hub comprises 4 prongs disposed at 0 degrees, 60 degrees, 120 degrees, and 180 degrees, measured from a transverse axis perpendicular to the axial axis and passing, through the center of the central body.
 10. The hub of claim 1, wherein the hub comprises 5 prongs disposed at 0 degrees, 72 degrees, 144 degrees, 216 degrees, and 288 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.
 11. The hub of claim 1, wherein the hub comprises 6 prongs disposed at 0 degrees, 60 degrees, 120 degrees, 180 degrees, 240 degrees, and 300 degrees, measured from a transverse axis perpendicular to the axial axis and passing through the center of the central body.
 12. The hub of claim 1, wherein the top side comprises a circular cylindrical protrusion.
 13. The hub of claim 1, wherein a radius of curvature of the spherically concaved section is equal to 120 inches.
 14. A hub-strut assembly comprising the hub of claim 1 and two or more struts coupled with the two or more prongs.
 15. The hub-strut assembly of claim 14, wherein each of the two or more struts comprise a tubular circular cylindrical pipe.
 16. The hub-strut assembly of claim 15, wherein at least one of the tubular circular cylindrical pipes is inserted into the first straight segment of one of the two or more prongs.
 17. The hub-strut assembly of claim 15, wherein the first straight segment of at least one of the two or more prongs is inserted into one of the tubular circular cylindrical pipes.
 18. A dome assembly comprising a plurality of the hub-strut assembly of claim
 14. 19. A method of constructing a unitary hub for a dome, comprising: (a) providing two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment; wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle; wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter; and (b) joining the two or more tubular circular cylindrical prongs to form a central body, said two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body: wherein the hub comprises a top side and a bottom side; and wherein the surface of the bottom side comprises a spherically concaved section having a curvature.
 20. A method of assembling a dome, comprising: (a) providing a plurality of unitary hubs, each unitary hub comprising: (i) two or more tubular circular cylindrical prongs each comprising a first straight segment and a second straight segment; wherein the first straight segment is tilted with respect to the second straight segment thereby making a segment angle; wherein the first straight segment has a first inner diameter and a first outer diameter and the second straight segment has a second inner diameter and a second outer diameter; and (ii) a central body formed from joining the two or more tubular circular cylindrical prongs disposed around an axial axis through a center of the central body; wherein the hub comprises a top side and a bottom side; and wherein the surface of the bottom side comprises a spherically concaved section having a curvature; (b) providing a plurality of struts coupled with the two or more prongs of each of the unitary hubs. 